SPRAY IRRIGATION SYSTEMS USED FOR DISPOSAL OF
VEGETABLE PROCESSING WASTEWATER IN WISCONSIN
David K. Sauer, Environmental Engineer
Bureau of Water Quality
Wisconsin Department of Natural Resources
Madison, Wisconsin 53707
Expressed in 1979 farm value dollars, approximately $105 million worth of canned
and frozen vegetables were produced in Wisconsin during 1979 [1]. Wisconsin also ranked
first in the country for the production of peas, green and wax beans and beets in 1979
and was second in the production of sweet corn and cabbage for sauerkraut. In terms of
harvested acreage of vegetables, Wisconsin continues to rank number one in the country
during 1979 [1].
Processing of these vegetable products results in the generation of a significant volume of
wastewater. Individual operations within the plant such as washing, grading, cutting, peeling,
transporting, rinsing and cooling all require the use of water. Previous studies have been
made to establish the volume and the resulting strength of the wastewater generated for
particular vegetable products [2, 3]. These volumes and strengths, however, often vary from
plant to plant due to different degrees of water conservation and recycling.
The length of the vegetable processing season in Wisconsin is approximately 90 days extending from July 1 through September 30. This fact largely influences the method of
treatment for the processing wastewater. Treatment methods most often used include
aerated lagoons with discharge to surface waters and/or spray irrigation of wastewater
directly to the land. The seasonal nature of the vegetable processing business eliminates
the successful and economical use of other treatment processes such as activated sludge
systems and/or chemical treatment.
EXPERIMENTAL PROCEDURES
Information and data collected for this paper was compiled from reports submitted by
industry to the Wisconsin Department of Natural Resources (DNR). The amount of information required by the state is specified in each industry's Wisconsin Pollutant Discharge
Elimination System (WPDES) permit. Chapter 147, Wisconsin Statutes requires a permit for
the lawful discharge of any pollutant into the waters of the state which include groundwaters by definition. The Federal Water Pollution Control Act Amendments of 1972,
P. L. 92-500, requires a permit for the lawful discharge of any pollutant into navigable
waters. Therefore, in Wisconsin, permits are required for discharges from point sources to
surface water of the state and additionally to land areas where pollutants may percolate,
or seep to, or be leached to, groundwaters [4].
Information and data collected for the years 1977, 1978 and 1979 form the basis of this
paper. In addition to the permit required information described above, system design information was gathered from plan approvals on record for existing systems. Detailed soils
information for individual spray irrigation fields was gathered through the plan approvals
and the use of published soil survey maps [5]. Information collected during plant
inspections and compliance monitoring surveys by personnel from the Wisconsin DNR was
also used in the write up of this paper.
Installation of groundwater monitoring wells and monitoring of the groundwater lor
land disposal of liquid wastes is established under Wisconsin Adminstrative Code Chapter
NP 214 [6], Monitoring of the groundwater is dependent upon the volume and strength
of the wastewater discharged and also upon the soil and geological conditions of the particular land disposal system.
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